HOUSTON —
Mexican officials say a shipment of highly radioactive waste has been found near an abandoned stolen truck that was carrying the material. Authorities have not yet detained any suspects.

Mexican authorities say they found the white cargo truck in a parking lot, and found the container that held the radioactive material at another location. They say there was still some cobalt-60 inside, but that they also found a small quantity outside the container.

The radioactive medical waste came from a hospital in the northern border city of Tijuana and was being taken to a radioactive waste disposal site in central Mexico when two armed men hijacked the truck north of Mexico City on Tuesday. Cobalt-60 is used for medical therapy under controlled conditions in a hospital, but authorities say that someone exposed to it without proper protection would likely die, perhaps in a matter of minutes. Mexican authorities have yet to locate the suspects, dead or alive.

Police investigators speculate that the thieves may have been after the truck rather than the cargo. Fred Burton, a security analyst with Stratfor, a private intelligence firm in Austin, Texas, agrees.

"We certainly do not know the motivation for the theft of the truck and it very well may have been just that kind of truckjacking or carjacking kind of scenario, where the criminals who took this simply did not know what was being carried in the actual load," said Burton.

While it could not be used to produce a nuclear bomb, Fred Burton said that cobalt-60 could be used in a so-called "dirty bomb," in which conventional explosives scatter radioactive material over a large area.

"This is the kind of nightmare that DHS [Department of Homeland Security] here in the United States has been concerned about for quite some time and, of course, you also have the worry of that kind of material making its way to a port of entry in the United States as well," continued Burton.

Burton said that U.S. ports of entry have for several years used highly sensitive devices to detect radioactive material.

Cobalt-60 and other radioactive substances have caused numerous deaths and illnesses around the world in past incidents in which material was either stolen or accidentally left in a place accessible to the public.

In the 1970s, some errant radioactive metal was used in contraction poles and even furniture in Mexico, but authorities tracked it down before it caused a widespread health problem. In Brazil in 1987, some material was left by mistake at a hospital that had been vacated and some local residents took it to their homes to watch it glow at night. Four people died in that incident and more than 200 others suffered from radiation poisoning.